Fluid flow control devices such as fluid regulators are commonly employed in a variety of applications to ensure that fluid is delivered from a source to a destination without exceeding a predetermined control pressure. That is, typical pressure regulators reduce the pressure of fluid supplied from a source down to a control pressure that is suitable for the intended application.
Generally speaking, regulators are utilized in systems that are continuously pressurized. For example, in the off-shore oil and gas industry, hydraulic regulators are incorporated onto umbilical lines that feed high-pressure hydraulic fluids to subsea equipment located miles away. During normal operation, the umbilical line is fluid-filled and pre-pressurized such that the regulator simply operates to ensure that the pressure in the umbilical line does not exceed the control pressure.
Upon start-up, however, the umbilical lines are usually filled with fluid at the time they are hooked up to the regulator, but the fluid is not necessarily pressurized. Therefore, once connected, it is necessary to pressurize the line, which requires exposing the regulator to high pressure/high flow inlet and low pressure outlet conditions. Typical regulators are not designed to handle such flows and, moreover, pressurization can take longer than desired. To accommodate these situations, the fluid system can be equipped with a bypass circuit that is piped away from the regulator. Typically, a bypass circuit includes a manual valve piped between an inlet pipe that draws fluid away from the regulator and a return pipe that returns the fluid to the fluid system downstream of the regulator. Once the umbilical line or other line located downstream of the regulator is sufficiently pressurized, an operator manually closes the bypass circuit to redirect all of the fluid flow through the regulator during normal operation.